Between 1980 and 1988, the nation's health care costs more than doubled, from approximately $250 billion to just over $540 billion. This amount represents an increase from 9.1 percent to 11.1 percent of the gross national product (Office of National Cost Estimates, 1990). Employers, who pay for the major share of health care in the United States through employment-related hinge benefits, are increasingly turning to self-insurance and relying more heavily on managed care alternatives such as Health Maintenance Organizations (HMOs) and Preferred Provider Organizations (PPOs) in an attempt to contain these costs. In spite of these and other cost containment measures, the nation's health care costs am expected to continue to soar. HMO experienced rapid growth through the 1980s, but the rate of growth has slowed with the creation of more diverse models of managed cam that combine elements of traditional fee-for-service (FFS) and prepaid models. During the period of rapid HMO growth, a substantial amount of research was devoted to comparing the choice and cost of HMOs to FFS insurance. Although much research remains to be done on prepaid plans, it is important to study the choice and cost factors associated with different forms of experience-rated, fee-for-service insurance. We propose to study FFS insurance at the employer level using data from the 1989 Survey of Health Insurance Plans (SHIP), sponsored by the Health Care Financing Administration (HCFA). The 1989 SHIP was a nationwide survey of employers that gathered detailed, plan-specific information. Although our analyses will include HMOs, we will focus on fee-for-service plans. The specific aims of the research are to answer the following research questions: 1 . What factors determine who offers health insurance and who does not? 2. Among those employers that offer insurance, what factors determine who offers an HMO or a PPO? 3. Among those that offer a fee-for-service plan, what factors explain the decision to self-insure? 4. Do survey respondents classify their plans as self-insured on the basis of the risk they face or on the basis of who administers the plan? 5.What plan and organizational characteristics explain differences in health insurance costs per subscriber? Our results will provide new insights into the determinants of health care cost and will aid policymakers in evaluating the impact of new legislative initiatives on controlling costs.